The storage-life of oxidatively-degradable foodstuffs such as fish, meat, poultry, bakery goods, fruits, grains, and vegetables is limited in the presence of a normal atmospheric environment. The presence of oxygen at levels found in a normal atmospheric environment leads to changes in odor, flavor, color, and texture resulting in an overall deterioration in quality of the foods either by chemical effect or by growth of aerobic spoilage microorganisms.
Modified atmosphere packaging (MAP) has been used to improve storage-life and safety of stored foods by inhibition of spoilage organisms and pathogens. MAP is the replacement of the normal atmospheric environment in a food storage pack with a single gas or a mixture of gases. The gases used in MAP are most often combinations of oxygen (O2), nitrogen (N2), and carbon dioxide (CO2). In most cases, the bacteriostatic effect is obtained by a combination of decreased O2 and increased CO2 concentrations. Farber, J. M. 1991. Microbiological aspects of modified-atmosphere packaging technology: a review. J. Food Protect. 54:58-70.
In traditional MAP systems, the MAP gas composition is not manipulated after the initial replacement of the normal atmospheric environment. Thus, the composition of the gases present in the food pack is likely to change over time. Changes in the gas portion of the packaging can be due to diffusion of gases into and out of the product, diffusion of gases into and out of the food pack, and the effects of microbiological metabolism. In certain cases, the foodstuff will absorb carbon dioxide (CO2) reducing the amount of CO2 in the gas portion of the packaging with a concomitant increase in the relative amounts of other gases such as oxygen. Carbon dioxide absorption can lead to a negative pressure in the tote creating a “vacuumizing” situation which could potentially damage the foodstuff by, e.g., reducing the carbon dioxide concentration below levels effective for inhibiting microbial spoilage of the foodstuff with corresponding increases in residual oxygen concentrations. Vacuumization caused by CO2 absorption can also cause leakage, especially in rigid totes, resulting in failures.
These architectures, which are usually small in size, generally dictate a one-time (multiple gas flush event) as they do not have any valves or fittings to facilitate the initial or additional gas flushes after the initial gas flush process. Furthermore, multiple gas flushes are not economically viable due to the necessity of reasonable production throughput requirements. Since these architectures are generally small, easily handled packages (usually 40 pounds or less) the cost per pound to employ the MAP process is very high and resulting MAP gas mixture less than ideal for maximum shelf life extensions.
An improvement to the above is disclosed in U.S. Ser. No. 11/769,944 where a fuel cell is integrated with a tote comprising oxidatively degradable foodstuffs and an internal hydrogen source. The fuel cell operates to convert excess oxygen in the tote to water by reaction with hydrogen. Nevertheless, the totes of that application require a single gas flush prior to sealing the tote.
Thus, the art to date can be generally characterized as sealed systems which do or do not remove residue oxygen from the interior of the system by chemical, electrical or catalytic processes.
It would be beneficial to avoid the functional and economic deficiencies of existing processes for removing oxygen from such storage systems. And there is a need to remove residual oxygen from such storage systems.